THE CIRCULATORY SYSTEM The TRANSPORT or CIRCULATORY system connects all other systems. This system performs four (4) principal functions: · · · ·

Transportation of oxygen and carbon dioxide Distribution of nutrients and transportation of wastes Maintenance of body temperature Circulation of hormones

Structure of circulatory system Three general components: · FLUID (blood) in which materials are transported · System of BLOOD VESSELS in which the fluid moves in · PUMP – (heart) that pushes fluid throughout system The cardiovascular system = heart + blood vessels + blood BODY STATS:

HEART: 300 grams (size of fist) BLOOD: body contains five liters (5L) RATE: beats 72 per minute CIRCULATORY SYSTEM: two systems in one a) Pulmonary circuit: b) Systemic circuit:

blood from RIGHT side (low OXYGEN) pumped to LUNGS to pick up oxygen (release CO2) blood from LEFT side (high OXYGEN) pumped through body

Heart Structure HEART: a double pump a) RIGHT: pulmonary circuit b) LEFT: systemic circuit A large MUSCLE called the SEPTUM separates both sides. The heart is divided into four (4) chambers: · ·

ATRIA: VENTRICLES:

top two chambers, thin walls, RECEIVE blood bottom two chambers, thick walls, PUMP blood

VALVES: these are found between atria and ventricles and where ventricles empty into arteries that leave the heart ex. Atrioventricular valves: a) bicuspid valve- between RA and RV b) tricuspid valve- between LA and LV Semilunar valves: found between ventricles and arteries Function of Valves: to ensure blood flows in ONE DIRECTION only - prevents blood from going the wrong way

HEART RHYTHMS, SOUNDS, AND PRESSURES PACEMAKER:

SA (sinoatrial) node - bundle of nerves controlling heart beat (72) AV (atrioventricular) node - passes the nerve impulses to the ventricles so they contract in unison

Heart Sounds: LUBB-DUBB sound:made when heart valves CLOSE a) LUBB -- when atrioventricular valves close b) DUBB – when semilunar valves close Pressures in the heart a) DIASTOLE – the atria RELAX and fill with blood (low pressure) - produces diastolic pressure c) SYSTOLE – the ventricles CONTRACT pushing blood into arteries - produces systolic pressure (high pressure)

BLOOD PRESSURE: -

measured with an instrument called a sphygmomanometer units: mm of Hg (mercury)

Two pressures:

a) systolic b) diastolic

120 80

mm Hg

HYPERTENSION: high blood pressure - dangerous - destruction of blood vessels (fatal = aneurysm) LOW blood pressure: - poor transport of important materials throughout body

BLOOD VESSELS

There are THREE main types of blood vessels: 1.

2.

ARTERIES: · · · · ·

carry blood AWAY from the heart THICK walls (extra muscle) blood under high pressure largest called the AORTA most have HIGH amounts of OXYGEN except pulmonary artery (low O 2 – goes to lungs)

·

ARTERIOLES: small arteries

CAPILLARIES: · · ·

3.

smallest blood vessels where exchange of materials between blood and cells occurs one cell thick

VEINS: · · · ·

carry blood BACK to the heart THIN walls (less muscle) blood under LOW pressure contain VALVES to keep blood moving in one direction

·

VENULES:

small veins

Blood flow through vessels: Heart à arteries à arterioles à capillaries à EXCHANGE à venules à veins à heart

BLOOD COMPONENTS Normal adult contains about five liters (5L) of blood. Blood:

·

PLASMA:

55 % liquid 45 % cells

- called PLASMA - 1 % WBC (white) , rest are RBC (red)

functions – carries dissolved nutrients, hormones, wastes, and antibodies

BLOOD CELLS: ·

·

·

WBC: -

white many types, called LEUKOCYTES function: protect the body from invading microorganisms and toxins cells have a nucleus

RBC: - red - contain hemoglobin: an iron-containing protein which helps blood carry OXYGEN and CARBON DIOXIDE - with oxygen the blood is bright red - with carbon dioxide blood is dark red - cells do NOT have a nucleus PLATELETS:

- small cell fragments (not really true cells) - job: help blood CLOT by working with SERUM proteins